Evaluation of Existing and Modified Wetland Equations in the SWAT Model

The ability to accurately simulate flow and nutrient removal in treatment wetlands within an agricultural, watershed‐scale model is needed to develop effective plans for meeting nutrient reduction goals associated with protection of drinking water supplies and reduction of the Gulf of Mexico hypoxic zone. The objectives of this study were to incorporate new equations for wetland hydrology and nutrient removal in Soil and Water Assessment Tool (SWAT), compare model performance using original and improved equations, and evaluate the ramifications of errors in watershed and tile drain simulation on prediction of NO₃‐N dynamics in wetlands. The modified equations produced Nash‐Sutcliffe Efficiency values of 0.88 to 0.99 for daily NO₃‐N load predictions, and percent bias values generally less than 6%. However, statistical improvement over the original equations was marginal and both old and new equations provided accurate simulations. The new equations reduce the model's dependence on detailed monitoring data and hydrologic calibration. Additionally, the modified equations increase SWAT's versatility by incorporating a weir equation and an irreducible nutrient concentration and temperature coefficient. Model improvements enhance the utility of SWAT for simulating flow and nutrients in wetlands and other impoundments, although performance is limited by the accuracy of inflow and NO₃‐N predictions from the contributing watershed. Editor's note : This paper is part of the featured series on SWAT Applications for Emerging Hydrologic and Water Quality Challenges. See the February 2017 issue for the introduction and background to the series.     

Synthesis,Characterization and Nanocomposite Formation of Poly(glycerol succinate-co-maleate) with Nanocrystalline Cellulose

A novel biodegradable polymer based on glycerol, succinic anhydride and maleic anhydride, poly(glycerol succinate-co-maleate), poly(GlySAMA), was synthesized by melt polycondensation and tested as a matrix for composites with nanocrystalline cellulose. This glycerol-based polymer is thermally stable as a consequence of its targeted cross-linked structure. To broaden its range of properties, it was specifically formulated with nanocrystalline cellulose (NCC) at concentrations of 1, 2 and 4 wt%, and showed improved mechanical properties with NCC. Specifically, the effect of reinforcement on mechanical properties, thermal stability, structure, and biodegradability was evaluated, respectively, by tensile tests and thermogravimetric analyses, X-ray diffraction and respirometry. The neat poly(GlySAMA) polymer proved flexible, exhibiting an elongation-to-break of 8.8 % while the addition of nanowhiskers (at 4 wt%) caused tensile strength and Young’s modulus to increase, 20 and 40 %, respectively. Stiffness improved without significantly decreasing thermal stability as measured by thermogravimetric analysis. Biodegradation tests indicated that all samples were degradable but NCC reduced the rate of biodegradation.     

Sustainability Assessment for Agriculture Scenarios in Europe’s Mountain Areas: Lessons from Six Study Areas

Sustainability assessment (SA) is a holistic and long-range strategic instrument capable of assisting policy-making in electing, and deciding upon, future development priorities. The outcomes of an SA process become more relevant and strengthened when conducted with multi-stakeholder engagement, which provides for multiple dialogues and perspectives. This was the object of research of the SA team in the context of BioScene (Scenarios for Reconciling Biodiversity Conservation with Declining Agriculture Use in Mountain Areas in Europe), a three-year project (2002–2005) funded by the European Union 5th Framework Program, which aimed to investigate the implications of agricultural restructuring and decline for biodiversity conservation in the mountain areas of Europe, using three distinct methodological streams: the ecological, the socio-economic, and the SA approaches. The SA approach drew on the previous two to assess the importance for biodiversity management of different scenarios of agri-environmental change and rural policy in six countries (France, Greece, Norway, Slovakia, Switzerland, and the United Kingdom), develop causal chains, include stakeholder views, and identify potential contributions for, or conflicts with, sustainability. This article tells how SA was used, what sustainability meant in each study area through different objectives of sustainability considered, discusses the methods used in SA, and the benefits arising. The SA was conducted by a team independent of any study area, who developed and oversaw the application of the SA methodology, assisting national teams, and developing a cross-country understanding of the sustainability of proposed scenarios in the different geographical and social contexts, and their implications for policy-making. Finally, it reflects on the persistent challenges of interdisciplinary research, compounded by multi-cultural teams, and concludes on the BioScene’s lessons for the further development and application of SA.

Transportation-Related Volatile Hydrocarbon Source Profiles Measured in Atlanta

Abstract

Samples representative of transportation-related hydrocarbon emissions were collected as part of the 1990 Atlanta Ozone Precursor Monitoring Study. Motor vehicle emissions were sampled in canisters beside a roadway in a tunnel-like underpass during periods of heavy traffic. Airport and aircraft emissions were approximated by canister samples obtained at a major airport facility. Three octane grades of gasoline were purchased from six major vendors in Atlanta. Canister samples were prepared using these fuels to approximate the whole gasoline and gasoline vapor composition of the fuels in use during the study. All samples were analyzed by gas chromatography/flame ionization detection (GC/FID) for their hydrocarbon content. Detailed speciated hydrocarbon profiles were developed from this source sampling and analysis program for use in the Chemical Mass Balance (CMB) model. Profiles presented and discussed here represent the hydrocarbon composition of emissions from a roadway, composite headspace gasoline at two temperatures, composite whole gasoline, whole gasoline at three octane grades, and an airport. The roadway profile is compared with similar profiles in the literature, and recommendations are made regarding its use in the CMB model. The roadway and fuel profiles are discussed in the context of the MOBILE5 model outputs. The headspace gasoline vapor profile presented here is compared with a headspace gasoline vapor profile calculated from the whole gasoline profile by means of Raoult’s law. Agreement between the measured and calculated headspace profiles is excellent. The airport profile demonstrates the importance of high molecular weight volatile hydrocarbons in airport and aircraft emissions.     

Impact of “Designated Smoking Area” Policy on Nicotine Vapor and Particle Concentrations in a Modern Office Building

A series of measurements of nicotine vapor and particle concentrations were carried out in a modern office building. The measurement program was designed to document the impact of the new smoking policy (e.g. smoking restricted to two specific areas) on air quality in various parts of the building.

Measurements at over 30 locations examined areas where smoking was restricted, where smoking was permitted, and where an air handler shared the load of a designated smoking area. These measurements were taken at the same locations before and after the policy was Implemented.

The measurement results Indicated that: ? After the policy was implemented, general employee exposure to nicotine vapor (as a surrogate for all environmental tobacco smoke) was reduced by about 98 percent on most floors. Other patterns related to spillover from designated smoking areas and changes in the designated smoking areas themselves are described in the paper.

? Substantial reductions in exposure to nicotine vapor were found even for those general office areas which had the highest concentrations after the policy was implemented.

     

Annual and weekly patterns of ozone and particulate matter in Jeddah,Saudi Arabia

Air pollution has been an increasing concern within the Kingdom of Saudi Arabia and other Middle Eastern countries. In this work the authors present an analysis of daily ozone (O₃), nitrogen oxide (NO_x), and particulate matter (<10 μm aerodynamic diameter; PM₁₀) concentrations for two years (2010 and 2011) at sites in and around the coastal city of Jeddah, as well as a remote background site for comparison. Monthly and weekly variations, along with their implications and consequences, were also examined. O₃ within Jeddah was remarkably low, and exhibited the so-called weekend effect—elevated O₃ levels on the weekends, despite reduced emissions of O₃ precursors on those days. Weekend O₃ increases averaged between 12% and 14% in the city, suggesting that NO_x/volatile organic compound (VOC) ratios within cities such as Jeddah may be exceptionally high. Sites upwind or far removed from Jeddah did not display this weekend effect. Based on these results, emission control strategies in and around Jeddah must carefully address NO_x/VOC ratios so as to reduce O₃ at downwind locations without increasing it within urban locations themselves. PM₁₀ concentrations within Jeddah were elevated compared with North American cites of similar climatology, though comparable to other large cities within the Middle East.

Implications:Daily concentrations of O₃, PM₁₀, and NO_x in and around the city of Jeddah, Saudi Arabia, are analyzed and compared with those of other reference cities. Extremely low O₃ levels, along with a significant urban weekend effect (higher weekend O₃, despite reduced NO_x concentrations), is apparent, along with high levels of PM₁₀ within the city. Urban O₃ in Jeddah was found to be lower than that of other comparable cities, but the strong weekend effect suggests that care must be taken to reduce downwind O₃ levels without increasing them within the city itself. Further research into the emissions and chemistry contributing to the reduced O₃ levels within the city is warranted.     

Emissions concerns during renovation in the healthcare setting: Asbestos abatement of floor tile and mastic in medical facilities

Healthcare facilities undergoing renovation have specific concerns that are exacerbated when the restoration requires asbestos abatement of aged floor tile and mastic. The current state of the art for removal of these materials involves manual removal of floor tile and chemical stripping of mastic. Utilization of these stripping chemicals is a concern for facilities whose perception is based on a safe, caring, and healthy environment. In this study, wet grinding is evaluated as an alternative to chemical stripping of asbestos-containing floor tile mastic. This study endeavors to answer the question; what is the difference between these two methodologies in terms of their operational efficacy and suitability in the healthcare setting. Wet grinding and chemical stripping are evaluated in a side-by-side comparison using a mixed methods approach. The data shows that the methodologies are statistically similar in terms of their cost and emissions data. The data indicates that the benefits associated with the wet grinding method offer advantages that are not present using the chemical stripping method. This study also demonstrates that wet grinding is a viable alternative to chemical stripping especially in healthcare facilities.     

Solid waste management by application of the WAMED model

This article aims to develop a general model for the evaluation of ecological-economic efficiency that will serve as an information support tool for decision making at the corporate, municipal, and regional levels. It encompasses cost-benefit analysis in solid waste management by applying a sustainability promoting approach that is explicitly related to monetary measures. A waste managements’ efficient decision (WAMED) model based on cost-benefit analysis is proposed and developed to evaluate the ecological-economic efficiency of solid waste management schemes. The employment of common business administration methodology tools is featured. A classification of competing waste management models is introduced to facilitate evaluation of the relevance of the previously introduced WAMED model. Suggestions are made for how to combine the previously introduced EUROPE model, based on the equality principle, with the WAMED model to create economic incentives to reduce solid waste management-related emissions. A fictive case study presents the practical application of the proposed cost-benefit analysis-based theory to the landfilling concept. It is concluded that the presented methodology reflects an integrated approach to decreasing negative impacts on the environment and on the health of the population, while increasing economic benefits through the implementation of solid waste management projects.     

Behavior of an MBT waste in monotonic triaxial shear tests

Legislation in some parts of the world now requires municipal solid waste (MSW) to be processed prior to landfilling to reduce its biodegradability and hence its polluting potential through leachate and fugitive emission of greenhouse gases. This pre-processing may be achieved through what is generically termed mechanical–biological-treatment (MBT). One of the major concerns relating to MBT wastes is that the strength of the material may be less than for raw MSW, owing to the removal of sheet, stick and string-like reinforcing elements during processing. Also, the gradual increase in mobilized strength over strains of 30% or so commonly associated with unprocessed municipal solid waste may not occur with treated wastes. This paper describes a series of triaxial tests carried out to investigate the stress–strain–strength characteristics of an MBT waste, using a novel digital image analysis technique for the determination of detailed displacement fields over the whole specimen. New insights gained into the mechanical behavior of MBT waste include the effect of density on the stress–strain response, the initial 1-D compression of lightly consolidated specimens, and the likely reinforcing effect of small sheet like particles remaining in the waste.     

Phosphorus retention and remobilization in vegetated buffer strips: a review

Diffuse pollution remains a major threat to surface waters due to eutrophication caused by phosphorus (P) transfer from agricultural land. Vegetated buffer strips (VBSs) are increasingly used to mitigate diffuse P losses from agricultural land, having been shown to reduce particulate P transfer. However, retention of dissolved P (DP) has been lower, and in some cases VBSs have increased delivery to surface waters. The aims of this review were (i) to develop a conceptual model to enhance the understanding of VBS functioning in terms of DP, (ii) to identify key processes within the model that affect DP retention and delivery, and (iii) to explore evidence for the controls on these processes. A greater understanding in these areas will allow the development of management strategies that enhance DP retention. We found evidence of a surface layer in buffer strip soils that is enriched in soluble P compared with adjacent agricultural land and may be responsible for the reported increased DP delivery. Through increased biological activity in VBSs, plants and microorganisms may assimilate P from particulates retained in the VBSs or native soil P and remobilize this P in a more soluble form. These conclusions are based on a limited amount of research, and a better understanding of biogeochemical cycling of P in buffer strip soils is required.